The most short-lived of all of Britain’s constitutional experiments in India was the

All four measures are named acts of 1861, 1892, 1909 and 1919 respectively, enacted in that sequence by the British in India [1]. The Indian Councils Act of 1909 (Morley–Minto reforms) formally came into force in 1909 [2] and its key provisions were effectively superseded by the Government of India Act, 1919 (Montagu–Chelmsford reforms), which reconstituted central and provincial legislatures and introduced dyarchy from 1919 onwards [4]. Because the 1909 Act was introduced in 1909 and replaced by the more comprehensive 1919 measure, it was the shortest-lived of these constitutional experiments—lasting roughly a decade between enactment and supersession [3].

Sources

1. [1] Indian Polity, M. Laxmikanth(7th ed.) > Chapter 1: Historical Background > Indian Councils Act of 1861 > p. 4
2. [2] https://en.wikipedia.org/wiki/Indian_Councils_Act_1909
3. [3] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 26: Constitutional, Administrative and Judicial Developments > Government of India Act, 1919 > p. 509
4. [4] https://en.wikipedia.org/wiki/Legislatures_of_British_India